The present invention relates to delivery appliances for delivering an expandable annular device to a desired location in a lumen. The invention is particularly useful in medical applications, for delivering an expandable intraluminal device, especially an intravascular device, to a desired location in the lumen of a subject""s body, and is therefore described below with respect to such an application.
Numerous types of implantable intravascular devices, such as stents, grafts, sensors, and filters are well known in the prior art. Also well known are delivery systems and methods for guiding these devices to the proper location within the body and for deploying them at the desired location, as described, for example, in U.S. Pat. Nos. 6,221,043; 4,950,227; 5,634,928; 5,108,416; and 5,549,613. Such delivery systems typically include balloon-type catheters, in which the balloon is deflated to receive the intravascular device and to deliver it to the desired location, and then inflated to expand the intravascular device and thereby to press it firmly against the walls of the lumen. After the intravascular device has been so deployed, the balloon is again deflated in order to remove the catheter from the lumen, leaving the intravascular device deployed within the lumen.
However, in the type of deployment procedure disclosed in these patents, the balloon, when completely expanded, blocks the lumen during the procedure of implanting the device, and thereby prevents the flow of blood. This can be extremely hazardous or even fatal.
Perfusion balloon catheters, which permit partial flow of bodily fluids such as blood past an inflated balloon, are also well known in the art and are use for angioplasty. In this type of catheter, the balloon is formed such that, when inflated within a bodily cavity, one or more channels are provided for the flow of bodily fluids or blood past the inflated balloon. Perfusion balloon catheters are generally not used for implanting intraluminal devices, but rather for the opening of a stenotic artery as a part of the Percutaneous Transluminal Angioplasty (PTA) procedure. When the balloon in a perfusion flow system is inflated, the central part of the lumen is blocked as in the other systems of the prior art, but a small channel is provided, usually in the form of a helix, between the expanded balloon and the wall of the lumen. Typical perfusion balloon catheter systems are disclosed, for example, in U.S. Pat. Nos. 6,245,040; 5,108,370; and 5,232,446.
In some situations, for example in the deployment of self-expandable intraluminal devices in the aortic arch or in the intracranial arteries, the complete blockage of the lumen by the balloon during the implantation process, even for a short period of time, may also be highly hazardous or even fatal.
Another drawback in the use of a conventional balloon catheter for self-expanding intervascular devices is the danger of over inflation, which can cause significant damage to the intimal and the medial layers of the vessel wall, and increased restenosis of the intervascular devices. The use of a conventional balloon catheter in a large diameter vessel, such as the aorta, may also be problematical because of the difficulty of expanding the balloon to the large size required for this application with sufficient force to anchor the intravascular device in place without damaging the vessel walls.
An object of the present invention is to provide a delivery appliance, which is not based on an inflatable balloon, for delivering an expandable annular device to a desired location in a lumen. Another object is to provide a delivery appliance for delivering an expandable intraluminal device, particularly an intravascular device, to a desired location in a lumen of the vascular system of the subject""s body, which delivery appliance does not have the foregoing disadvantages of an inflatable-balloon type delivery appliance when used for such applications.
According to a broad aspect of the present invention, there is provided a delivery appliance for delivering an expandable annular device to a desired location in a lumen, comprising: an annular array of supporting strips extending from a proximal end of the annular array to a distal end of the annular array, to define an annular supporting surface for the expandable annular device, each of the supporting strips being laterally deformable to radially expand or radially contract the annular array and the annular supporting surface defined thereby; and a connecting stem passing through the annular array of supporting strips; the connecting stem having a distal end coupled to the supporting strips at the distal end of the annular array for axial movement therewith., and a proximal end passing through the proximal end of the annular array of supporting strips for axial movement with respect thereto; the proximal end of the connecting stem being axially movable in one direction to move the distal end of the annular array axially away from the proximal end of the annular array to radially contract the annular supporting surface; the proximal end of the connecting stem being axially movable in the opposite direction to move the distal end of the annular array axially towards the proximal end of the annular array to radially expand the annular supporting surface.
According to further features in the preferred embodiments of the invention described below, each of the supporting strips in the annular array is stiff in the longitudinal direction, but is formed with at least one integral hinge to permit its deformation in the lateral direction. More particularly, each of the supporting strips includes a strip of stiff material extending from the proximal end of the annular array to the distal end of the annular array and formed with at least one transversely-extending groove producing the at least one integral hinge. The transversely-extending groove is formed on one surface of the strip of stiff material to permit the strip to be laterally deformed more easily in the direction of that surface than in the opposite direction.
According to further features in the preferred embodiments of the invention described below, each of the supporting strips in the annular array is formed with at least one integral hinge at the proximal end of the annular array, and with at least one integral hinge at the distal end of the annular array, such that the intermediate portions of the supporting strips remain substantially parallel to the longitudinal axis of the annular array during the radial contraction and the radial expansion of the annular supporting surface defined by the supporting strips. In the described preferred embodiments, each of the supporting strips in the annular array is formed with two integral hinges at the proximal end of the annular array, and with two integral hinges at the distal end of the annular array.
According to still further features in the preferred embodiments of the invention described below, the delivery appliance further includes an outer sleeve receiving the annular array of supporting strips when the annular array is in its contracted condition to maintain them in its contracted condition until the outer sleeve is removed from the annular array of supporting strips. The expandable annular device is interposed between the outer sleeve and the annular array of supporting strips when the annular array is in its contracted condition.
In one described preferred embodiment, the proximal end of the stem, and the proximal end of the annular array of supporting strips, are both extended outwardly in the proximal direction to enable the proximal ends of the stem and of the annular array of supporting strips to be manually grasped in order to effect the axial movement in the one direction or in the opposite direction.
In a second described preferred embodiment, a spring is interposed between the proximal end of the stem and the proximal end of the annular array of supporting strips urging the proximal ends apart, such that removal of the outer sleeve causes the spring automatically to effect the axial movement in the opposite direction to expand the inner supporting surface and thereby the annular device supported thereon.
It will thus be seen that such a delivery appliance eliminates the need for an inflatable balloon, and therefore avoids many of the problems and difficulties, as described above, associated with such inflatable balloons. This make the delivery appliance particularly useful in medical applications for delivering intraluminal devices, especially intravascular devices.
Further features and advantages of the invention will be apparent from the description below.